The invention relates to a circuit grinding apparatus with a high-pressure roll press for the pressure disintegration of granular material, and with an integrated sifter or separator, whereby both units are surrounded by a housing consisting of two stationary lateral end walls, between which is arranged a material conveyor ring for an internal circulation of material, said conveyor ring being rotatably seated and capable of being set into rotation, whereby the inflow of material takes place through one or more openings in one or both housing end walls from the side, and the outflow of material likewise takes place laterally through one or more openings in the housing end wall.
Such an arrangement is disclosed in German patent application DE-A-196 30 687.6 (U.S. Ser. No. 08/844,583), which disclosure is incorporated herein by reference, in which a very compact circuit grinding apparatus with a two-roll press for pressure disintegration of granular material and with an integrated sifter was proposed. The two rolls of the roll press, in particular a high-pressure interparticle crushing roller mill, are thereby surrounded by a housing consisting of two stationary, i.e. non-rotating, lateral end walls, between which is arranged a material conveyor ring that is rotatably seated and can be set into rotation by a rotary drive, for an internal circuit of material. This rotatably seated material conveyor ring of the housing rotates at about e.g. 40 to 80% of the critical RPM, i.e., the ring takes along the press discharge material (scab material), according to the organization of lifter elements in the conveyor ring, up to the region approximately of the upper vertex point of the ring, and lets this material fall from above into the nip, by which means the internal material circuit arises. Bucket conveyors or other space-consuming conveyance means for transporting the press discharge material to the press inlet are omitted. With the rotating material conveyor ring, a multiple internal material circuit with multiple material bed stressing of the material is thus achieved in the smallest space and with a low outlay of machine equipment, whereby relatively high material circuit loads, due e.g. to reduced roller press pressure, taking into account the thereby increased stability of the rolls, are thereby to be managed.
In order to achieve greater finenesses in the grinding stock, in the housing of the compact circuit grinding apparatus of German published application DE-A-196 30 687.6 there is arranged the rotatably seated rod-type basket of a dynamic rod-type basket sifter, lying horizontally above the roller press, whereby the rod-type basket, through which sifting air flows, acquires the press discharge material discarded from the region of the upper vertex point of the material conveyor ring, and separates out the coarse grain portion therefrom, which portion is then supplied to the rolls lying thereunder for purposes of further pulverization, while the sifter air, loaded with the fine material portion, is drawn off from the rod-type basket and separated from the sifter air outside the circuit grinding apparatus.